According to the Americam College of Allergy, Asthma, & Immunology:
- More than 50 Million people in the US have allergies
- Adults and children of any age can be tested
- Testing options include Skin tests, or Blood tests
- 2 types of skin tests:
- Drop of suspected allergen is scratched on the skin surface, usually on the back or forearm; can test many possible allergens at same time
- Tiny amount of suspected allergen is injected just under the skin (“intra-dermal”); intra-dermal allergy testing is restricted to testing for allergy to insect stings or penicillins
- For skin tests (both types), positive reactions usually appear within 20 minutes
- Both types of skin test have little or no pain; positive reactions can cause annoying itching red bumps, like a mosquito bite
- Note that some medications interfere with allergy testing – especially allergy meds like antihistamines
- Both kinds of allergy skin tests are thought to be mediated by a type of antibody (IgE) that we make against the allergen
- Allergy Blood Tests detect the presence of IgE that is made against an allergen.
The Allergy Blood Tests can be used when:
- Patient is taking a medication that can interfere with skin testing, but the medication cannot be stopped for a few days
- The patient suffers from severe skin condition such as eczema or psoriasis that would either be exacerbated by the testing, or interferes with interpretation of the results
- Testing with a strong allergen might cause an extra large positive reaction
- For babies and young children, a single needle stick to draw a small amount of blood to be used for allergy blood testing may be better tolerated than several skin tests
- Allergy blood tests can take many days to get results
- Allergy blood tests are generally less sensitive than skin testing methods
Which Test is Better?
Each test type has pluses and minuses. Using either type of test, the results alone do not diagnose allergies. Like all test results, they must be interpreted with the medical history.
The Benefits of Testing:
Some people with severe allergic rhinitis, sinusitis, otitis, or asthma (think Unified Airway Disorders), that is not controlled with standard therapy may benefit from allergy testing, if test results enable allergen avoidance or help guide allergy treatment using immunotherapy – either sub-cutaneous or sub-lingual immunotherapy (SCIT or SLIT).
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For More Information on Allergy Testing:
- Allergy Testing. A Review by JAMES T. LI, M.D., PH.D., Mayo Clinic; Published in:
Am Fam Physician. 2002 Aug 15;66(4):621-625:
- Allergy Testing, According to the American College of Allergy, Asthma, & Immunology:
- From this blog: How Rhinitis, Asthma, Sinusitis, Tonsillitis, Otitis, Are All Connected – the Unified Airway:
Wolfgang Ihloff: http://de.wikipedia.org/wiki/Benutzer:Wolfgang_Ihloff
Hi, I’m Russell Faust, author of this medical education blog.
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